Uranium solution spill at Tricastin

09 July 2008

A spill at France's Tricastin site has led to uranium entering local rivers. Locals were initially advised not to use river water or to eat fish, but radiation protection authorities now say effects should be negligible.

Tricastin from afar (Image: IRSN)

The incident occurred at about 11pm on 7 July at a decontamination facility operated by Areva subsidiary Socatri. The company specialises in maintaining and dismantling nuclear equipment while cleaning and recovering uranium contamination.

About 30 cubic metres of stored decontamination solution containing 12 grams of uranium per litre escaped. The fluid overflowed from one tank into another one designed for this purpose but the secondary tank was not watertight and the fluid leaked out of the plant and into the ground.

Socatri workers reacted by notifying the Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) and drilling a borehole in the immediate facility of the spill to begin to assess potential environmental impacts.

Knowing that the solution would travel through storm drains and reach the Gaffière and Lauzon rivers before the Rhône, a precautionary measure taken immediately by the ASN was to advise authorities in the Drôme and Vaucluse regions to restrict fishing and the use of river water by the public. The ASN said it did this without waiting for the outcome of tests, adding that eating fish from the rivers would anyway have very limited effects on health.

Staff from the Institute for Radiological Protection and Nuclear Safety (Institut de Radioprotection et de Sûreté Nucléaire, IRSN) were dispatched to the site to take environmental measurements. Seven surface tests and nine groundwater tests showed contamination levels to be receding rapidly, although Socatri's initial test showed radiation in groundwater to be 1000 times higher than the World Health Organization's (WHO's) 15 micrograms of uranium per litre guideline for water intended for human consumption. IRSN said it "believes the radiological consequences for people should be neglibile."

An Areva announcement late on 9 July said surface water samples taken off site and in the Gaffière and Lauzon rivers showed a "significant decrease in uranium levels at all sampling points." The majority of samples showed uranium levels were below the WHO guideline for drinking water, the company said, with the highest sample reaching 31.2 micrograms per litre. "Water samples from the aquifer show no abnormality," Areva concluded.

ASN has defined a monitoring plan and will visit the site on 10 July, while IRSN is to put ongoing water test results on its website. Areva said it had proposed to ASN that the incident be rated at Level 1 on the International Nuclear Event Scale, an 'anomaly'.

Tricastin is a very large nuclear site, home to four power reactors, the Comhurex uranium conversion facility, the Eurodif enrichment plant and the Pierrelatte weapons facility, operated by the Atomic Energy Commission, (Commissariat à l'énergie atomique, CEA).